1. Field of the Invention
The present invention relates to a quick-release system, in particular for a cycle. The invention also relates to a complete quick-release device, also commonly called “quick-release axle”, and to a wheel including such a device.
2. Description of Background and Other Information
In the field of cycles, it is known to use quick-release devices to assemble a component on a portion of the cycle quickly, such as a wheel to a fork, for example. These devices eliminate the need to use special tools, such as wrenches or the like. The quick-release devices can be used on a front wheel as well as on a rear wheel of a bicycle. The fastening device can also be used to secure various components on a cycle, such as a saddle to a seat tube.
Various existing quick-release systems are commonly used. The most widespread family of these devices includes those with a lever acting on a cam to exert a tightening force that is a function of the geometry of the cam and of the manual pre-adjustment of the center distance. In particular, the device includes a threaded rod commonly referred to as a “quick-release skewer,” having, at a first end, a movable or fixed stop, such as a tightening nut and/or a cam, and its other end, a quick-release mechanism including a lever mounted along an axis perpendicular to the axis of the skewer, an adjustable nut, and an intermediate cam. Various embodiments exist. In certain cases, the cam is integral with the lever; in other cases, it can be a separate element.
In all examples of these devices, the tightening force is obtained when the cam is driven by pivoting the lever in the direction of the skewer, from an opening position to a folded closed position. Before the lever is brought to the closed position, the tightening force is usually adjusted by screwing the release mechanism on the skewer. This adjustment is carried out by means of a nut that is part of the mechanism, which determines the center distance between the two tightening surfaces of the device, on each side of the skewer.
These devices pose a number of problems. Initially, they do not enable a good control of the tightening force, which can vary substantially depending upon the adjustment of the center distance, by the user, by means of the adjustment nut of the quick-release mechanism. A center distance adjusted to be too long at the outset can produce an insufficient tightening and thus cause a possible safety problem. The skewer fulfills the function of a tension spring, and its elasticity enables it to withstand the tension forces. An adjusted center distance adjusted to be too short, on the contrary, can cause an axial tension force on the skewer that is too substantial, and thus a risk of rupture of the skewer or breakage of another element of the device. A too substantial tension force also produces compression forces on the hub bearings. As a result, the bearings may be compressed and therefore damaged, thus causing substantial friction in the hub. Moreover, a device of this type is not easy to use, and the user has to proceed by trial and error in adjusting the center distance in order to achieve the correct tightening.
Therefore, the magnitude of the tightening force is never the same, and it depends upon the pre-adjustment of the center distance by the nut, and therefore, for the most part, upon the user's strength. The tightening magnitudes can vary substantially, resulting in risks of loosening in the case of insufficient tightening or, conversely, of failure/breakage of the skewer, in the case of excessive tightening. In order to guarantee the resistance of the skewer against failing under very high torques, the skewer is generally made of a high strength material and is oversized compared to the intended use under normal forces. With equivalent resistance to failure, the skewer can be made of a lighter material, such as titanium, in order to reduce weight, in particular for competition bicycles. Oversizing the elements and/or using light-weight materials such as titanium is expensive.
Another problem associated with a device of this type comes from the difficulty of obtaining a correct orientation of the lever at the end of the tightening and the correct tightening force at the same time. It is indeed preferable to direct the lever so that it does not constitute a “hook” for becoming engaged with external elements (branches, banners, wire, etc.) during practice, which can cause loosening of the wheel or collisions and, consequently, a potential danger of falling.
U.S. Patent Application Publication No. 2007/0154286 relates to a quick-release device offering an easier use. It includes a rotationally actuatable lever configured to tighten an internal nut against the skewer. The lever is axially movable against the force of an elastic tensioning mechanism in order to be capable of being manually disengaged from the nut and of assuming an angular position that can be selected independent of the nut tightening state. Thus, the main advantage is to be able to facilitate the tightening action by repositioning the lever and/or enabling the final orientation of the lever without loosening the device. However, this device does not improve the control of the tightening force. All of the problems mentioned in relation to the lack of control of the tightening force thus subsist in this device. For example, the tightening of the device remains subject to the judgment of the user and remains dependent upon the user's physical strength.
U.S. Pat. No. 5,447,362 is also based on a system for increasing tightening by means of a lever mechanism. The improvement lies in providing a system for visualizing the tightening by increasing the displacement of a tube-shaped tightening indicator. However, although it provides an indication of the tightening value, such a device does not entirely solve the problems associated with excessive or insufficient tightening of the device.
Therefore, there exists a need to provide a solution for a quick-release device that solves problems found in the prior art.
In particular, there is a need to improve the control and management of the tightening force for the user, without this force being directly a function of the user's physical strength. In particular, there is a need to apply a tightening amplification that can actually be controlled and reproduced.
There also exists a need to provide the user with an indication of the correct tightening, this being an easily perceptible indication.
There is also a need to generally eliminate the possibility of applying an excessive tension force to the skewer of the device that can damage the elements and/or the need for oversizing or using expensive materials having exceptional mechanical characteristics. There is also a need to reduce the weight of the device.
There also exists a need to improve the tightening efficiency of a release device.
Further, there is a need to prevent or to make unlikely an ill-timed loosening of the release device, for obvious reasons of user safety.
Still further, there exists a need to allow for an easy repositioning of the lever of the device that is not dependent upon the tightening force exerted by the device.